Field of the Invention
The present invention relates to a material of a fuel injection nozzle or a fuel injection needle for an internal combustion engine, and also to a fuel injection nozzle or needle produced from the material, as well as to a method of producing the fuel injection nozzle or needle by forging.
Experiences show that the materials of the fuel injection nozzle or needle should exhibit, after the heat treatment, a hardness of not less than HRC 57 or equivalent, as well as a corrosion resistance equivalent to that of JIS SUS 440C.
Presently used materials such as JIS SUS 420 J2, SUS 440B and SUS 440C cannot simultaneously satisfy both requirements for high corrosion resistance and high forging property which is necessary when the fuel injection nozzle or needle is fabricated by cold or warm forging. More specifically, JIS SUS 420 J2, which has a comparatively high forging property, inconveniently exhibits inferior wear resistance due to the fact that the hardness is reduced as a result of quenching and tempering heat treatment, whereas, JIS SUS 440B and JIS SUS 440C, which exhibit high level of hardness after the heat treatment, fail to provide required forging property.